Size Distribution page
The Size Distribution information pane presents a histogram with the echoes from single fish. The calculations are based on the fact that different fish species have different echo strength. The echo strength also depends on the operating frequency you use. Use the Size Distribution page to define the properties for the histogram shown in the Size Distribution information pane.
How to open
The page is opened in the Information Pane Options dialog box. To open, select the button on the Active menu.
You can also open the page by selecting Setup in the information pane.
Prerequisites
The Information Pane Options dialog box is only available when an Inspection view is active.
Description
The settings provided by the Size Distribution page allow you to shape the vertical bars in the Size Distribution information pane to meet your own requirements. You can define the upper and lower limits, the accuracy, and the vertical resolution.
The measurement accuracy in the Size Distribution information pane depends on the vertical angle of the inspection beam. A beam that points nearly straight down corresponds to a traditional echo sounder. This gives the best accuracy since the fish is then viewed from above. If you use a smaller beam angle, you may see the fish from the front or back. This gives significantly smaller echoes, and thus low measurement accuracy.
Details
- Mode
The Mode function specifies if the histogram shall present the size distribution based on the fish size, echo strength, or fish weight.
- Follow Fish Gain Colour Scale
Select this option to let the threshold follow the minimum level defined on the Colour Scale page for the corresponding channel.
- Manual Scale
Choose the lower and upper limits (in dB) of the scale.
- Lower Limit
This function specifies the lower limit of the target strengths shown in the histogram. The value reflects the current mode you have chosen.
Example: If you have chosen the Length mode, and specifies 10 in this spin box, fish shorter than 10 cm will not be shown in the histogram.
- Upper Limit
This function specifies the upper limit of the target strengths shown in the histogram. The value reflects the current mode you have chosen.
Example: If you have chosen the Weight mode, and specifies 7000 in this spin box, fish heavier than 7 kg will not be shown in the histogram.
- Advanced Settings
- Apply to All Channels
Check this box to apply the current setting to all the channels on your ST90 system. In this context, the term channel is used as a common term to identify the combination of transceiver, transducer and operating frequency.